Presentation Abstract

Numerous extinctions reveal species tipping points where multiple pressures converge to cause a cascade to demise. This paper examines how multiple pressures impacting Southern Resident Killer Whales (SRKW) could lead to their rapid downward spiral to extinction. The most commonly cited impacts to this population are historically low abundance of chinook salmon prey, vessel disturbance from ships and boats, toxicant loads above established health effects thresholds, and risk of oil spills from increased vessel and rail oil transport. Inbreeding and a heavily skewed male biased sex ratio at birth compound these problems. Lack of prey increases nutritional stress and dependence on fat reserves, while decreasing concentrations of bioactive thyroid hormone (T3). Fat metabolism increases circulating lipophilic toxins, which can further decrease T3 concentrations. Collectively, these impacts appear to increase rates of spontaneous abortion and neonatal loss. They may also lead to immunosuppression with a likely rise in incidence of disease and mortality. Associated population decline inherently increases inbreeding, which can increase male sex ratio bias at birth. Reduced T3 may also affect sex ratio at birth. SRKW seasonal presence in the Salish Sea is declining, attributed to declining prey and increased whale-watch vessels. Breeding events within and between pods are commonly observed during these visits to the inland waters. Their decline in visits may limit opportunities for breeding with a more diverse gene-pool, which could further increase inbreeding and associated potential for male-biased sex ratio bias at birth. Chinook remain at the epicenter of all this, indicating an increase in Chinook salmon abundance to be the single most effective mitigation we can do to recover SRKWs. Salmon are sentinels of ecosystem imbalance spanning from toxic contaminants to habitat destruction. Creative and immediate solutions are essential to expedite the process of recovery and ensure the survival of this iconic species.

Session Title

Transboundary Actions to Address Threats to Southern Resident Killer Whales (SRKW)

Keywords

SRKW Nutrition, SRKW Toxins, SRKW Abortions

Conference Track

SSE9: Transboundary Management and Policy

Conference Name

Salish Sea Ecosystem Conference (Seattle, WA : 2018)

Document Type

Event

SSEC Identifier

SSE9-112

Start Date

4-4-2018 4:30 PM

End Date

4-4-2018 4:45 PM

Type of Presentation

Oral

Contributing Repository

Digital content made available by University Archives, Heritage Resources, Western Libraries, Western Washington University.

Geographic Coverage

Salish Sea (B.C. and Wash.)

Rights

This resource is displayed for educational purposes only and may be subject to U.S. and international copyright laws. For more information about rights or obtaining copies of this resource, please contact University Archives, Heritage Resources, Western Libraries, Western Washington University, Bellingham, WA 98225-9103, USA (360-650-7534; heritage.resources@wwu.edu) and refer to the collection name and identifier. Any materials cited must be attributed to the Salish Sea Ecosystem Conference Records, University Archives, Heritage Resources, Western Libraries, Western Washington University.

Type

text

Language

English

Format

application/pdf

Share

COinS
 
Apr 4th, 4:30 PM Apr 4th, 4:45 PM

Are Southern Resident killer whales on a path to extinction?

Numerous extinctions reveal species tipping points where multiple pressures converge to cause a cascade to demise. This paper examines how multiple pressures impacting Southern Resident Killer Whales (SRKW) could lead to their rapid downward spiral to extinction. The most commonly cited impacts to this population are historically low abundance of chinook salmon prey, vessel disturbance from ships and boats, toxicant loads above established health effects thresholds, and risk of oil spills from increased vessel and rail oil transport. Inbreeding and a heavily skewed male biased sex ratio at birth compound these problems. Lack of prey increases nutritional stress and dependence on fat reserves, while decreasing concentrations of bioactive thyroid hormone (T3). Fat metabolism increases circulating lipophilic toxins, which can further decrease T3 concentrations. Collectively, these impacts appear to increase rates of spontaneous abortion and neonatal loss. They may also lead to immunosuppression with a likely rise in incidence of disease and mortality. Associated population decline inherently increases inbreeding, which can increase male sex ratio bias at birth. Reduced T3 may also affect sex ratio at birth. SRKW seasonal presence in the Salish Sea is declining, attributed to declining prey and increased whale-watch vessels. Breeding events within and between pods are commonly observed during these visits to the inland waters. Their decline in visits may limit opportunities for breeding with a more diverse gene-pool, which could further increase inbreeding and associated potential for male-biased sex ratio bias at birth. Chinook remain at the epicenter of all this, indicating an increase in Chinook salmon abundance to be the single most effective mitigation we can do to recover SRKWs. Salmon are sentinels of ecosystem imbalance spanning from toxic contaminants to habitat destruction. Creative and immediate solutions are essential to expedite the process of recovery and ensure the survival of this iconic species.